One of conventional devices for detecting static electricity is disclosed in Patent Document 1.
In the device, a P-channel MOSFET and an N-channel MOSFET are provided in an insulated chassis, gates of the both MOSFETs are connected to each other, and electrode bodies, which are provide outside of the chassis, are electrically connected to a connection line, which electrically connects the gates to each other.
A cathode of an LED is electrically connected to a drain of the N-channel MOSFET. An anode of the LED is electrically connected to a positive electrode of a direct-current power supply, and a source of the N-channel MOSFET is electrically connected to a negative electrode of the direct-current power supply.
An anode of another LED is electrically connected to a drain of the P-channel MOSFET. A cathode of another LED is electrically connected to the negative electrode of the direct-current power supply, and a source of the P-channel MOSFET is electrically connected to the positive electrode of the direct-current power supply.
When a positively-charged object is moved and closed to the above described device, the N-channel MOSFET is turned on and the LED emits light.
On the other hand, when a negatively-charged object is moved and closed to the above described device, the P-channel MOSFET is turned on and another LED emits light.